Flowserve NRG 16-51 - Manual (Page 4)

4
Application
Usage for the intended purpose
The level electrodes NRG 6-5, NRG 7-5 and NRG 9-5 are used in conjunction with level switch
NRS -5 as high water level alarms for steam boiler plants and (pressurized) hot water installations.
A high level alarm prevents the water level from exceeding the preset max. water level (HW) and for this
purpose switches off e. g. the feedwater supply.
Function
When the level exceeds the max. water level, the level electrode enters the liquid and an alarm is
triggered in the level switch NRS -5. The switchpoint “High level (HW) exceeded” is dictated by the
length of the electrode rod.
The self-monitoring function ensures that an alarm will also be triggered if the electrode insulation is
contaminated or has developed a leak or if there is a malfunction in the electrical connection.
The level electrode is installed inside steam boilers, vessels or inlet lines of hot-water systems. The
protective tube mounted on site (see section Examples of Installation (pages 8, 9) ensures correct
functioning.
One level electrode NRG ...-5 can be installed together with one GESTRA water level limiting
electrode in a single protection tube or external level pot.
If the level electrode is installed in a level pot outside the boiler, make sure that the connecting lines
are rinsed regularly. In addition, the logic unit SRL is required to monitor the purging times and the
purging sequence.
If the connecting lines for steam ≥ 40 mm and water ≥ 00 mm, the installation is considered to be
internal. In this case the rinsing processes do not have to be monitored.